Clenbuterol belongs to a class of drugs known as sympathomimetics. These drugs affect the sympathetic nervous system in numerous ways. It is specifically a selective beta-2 sympathomimetic, stimulating the beta-2 receptors, which creates a thermogenic effect, directly stimulating fat cells and accelerating the breakdown of triglycerides to form free fatty acids.

Animal studies have also shown it to be quite anti-catabolic and/or anabolic which obviously leads to its attractiveness amongst bodybuilders – particularly during the pre-contest phase. However, it has to be said that these studies have been restricted to animals and there is little real evidence of Clenbuterol having muscle building/sparingproperties in humans. This does little to tarnish its reputation as a great adjunct anabolic – used both off-season and pre-contest.